The apparatus of the present application relates to a pipe belling machine of the type designed to receive and treat one end of a length of plastic pipe wherein the said end had been heated sufficiently to soften the plastic for bell forming purposes.
In prior art pipe belling apparatus, it was known to utilize a shaped mandrel of predetermined configuration within a pressure chamber in axial alignment with each length of pipe as the pipe was secured within the chamber. Suitable operating mechanism was provided to facilitate insertion of the mandrel within the heated pipe end for end shaping into the desired bell or hub-shaped configuration. After the pipe end and the mandrel had been properly associated, the openings to the pressure chamber were sealed in an automatic manner and pressure was introduced within the chamber and about the pipe whereby the previously softened pipe walls were uniformly pressed against the outer periphery of the mandrel by the pressure built up within the pressure chamber. In this manner, the pressure within the chamber was utilized to accurately and precisely impress the shape of the mandrel upon the interior periphery of the pipe end.
After the application of the pressure chamber forces for an adequate period of time to form the desired shape, the end of the pipe was cooled in a known manner to set the desired shape in the plastic. The pressure chamber seal was then released to relieve the pressure and to provide a pressure chamber opening of sufficient size to thereby permit withdrawal of the shaped pipe from the pressure chamber.
The present applicant has previously invented apparatus and method for employing a pressure chamber for pressure forming a bell shape in plastic pipes as above described and as set forth in U.S. Pat. No. 4,277,231, dated July 7, 1981 and U.S. Pat. No. 4,353,860, dated Oct. 12, 1982. A copy of each of the applicant's patents is annexed hereto and made part hereof.